The long-term deformation rule of the embankment can reflect the impact of environmental factors on the embankment during different periods, and the deformation rule of the embankment is also the ultimate expression of embankment structure change under the interaction of various environmental factors. This study presents two classification methods for such deformation rules, which are based on long-term deformation monitoring data spanning 2006-2020, and obtained from 39 embankment sections along the Qinghai-Tibet Railway (QTR). The deformation rules of railway embankments in permafrost regions can be classified into five categories based on the accumulated deformation: slight heave, slight settlement, slow settlement, rapid settlement, and damage type. In addition, the curve trend of the embankment deformation can be used to categorize the deformation rules into five types: linear, step, fluctuating, U-shaped, and heave. The formation mechanism and characteristics of each type are summarized and analyzed. The results indicate that the linear type is the most unstable type, and the embankment experiences continuous and significant settlement deformation. Finally, two prediction models are established for the long-term deformation rules of embankments in permafrost regions. These models are used to establish the relationship between the early deformation rates and long-term deformation rules of the embankment, and can be used to predict whether the deformation rule of an embankment after 10 years of completion is linear. This study aims to provide early decision support for embankment stability evaluation, deformation prediction, reinforcement, and other studies in permafrost regions.

Nanofluid is an emerging heat transfer fluid with good heat transfer and thermal conductivity properties. It is important to investigate the phase change properties and morphological evolution during the freezing of nanofluid droplets to understand their practical applications. The effect of dynamic wettability on the deformation of a single droplet of aluminum trioxide (Al2O3-H2O) and graphene (CNT-H2O) nanofluids at different mass concentrations and substrate temperatures was investigated by visualizing the droplet freezing. The formation of solid-like and freezing front motions inside the droplet during the freezing process of these droplets was investigated. The solidification process was strongly influenced by the temperature gradient perpendicular to the cold surface and the change in the solid- liquid interface wettability during the phase change, resulting in volume redistribution at the top of the droplet. The freezing shape of Al2O3-H2O nanodroplets resembled a moon crater, and the influence of wettability decreased with increasing concentration, leading to a relative increase in the aperture of the top platform. The fully frozen state of the nanofluid droplet had an increasingly pointed tip, with a strong relationship between the substrate temperature and solidification time when the CNT-H2O concentration was 5 times higher and showed no change in the freezing droplet deformation rate under the experimental conditions. The contact angle of the two nanofluid droplets did not fluctuate significantly with increasing concentration, while that of the 1% nanofluid droplets remained at an average value of 85 degrees during freezing. Under different freezing conditions, the freezing shape of Al2O3-H2O droplets tended to increase in diameter as the subcooling temperature decreased, with the final deformation rate of 1% Al2O3-H2O being twice that at 5% concentration, while the contact angle of the same mass concentration of Al2O3-H2O decreased by 1 degrees as the subcooling temperature dropped. The CNT-H2O droplet became sharper at the tip as the subcooling temperature increased, and its contact angle did not change with temperature.